2. Introduction
• Plants need to protect themselves from various
threats. Hence, some plants have modified
parts that are used for defense.
• These defense mechanisms are used to protect
plants from herbivorous animals & insects &
also from insects laying eggs on the plant.
4. Thorns
• Thorns are
modified branches
or stems with a
sharpened point.
• Carissa bispinosa
is a plant that
possesses thorns as
a defense
mechanism.
5. Spines
• Spines are
modified leaves or
stipules.
• Spines modified
from leaves are
seen in Opuntia sp
• Spines modified
from stipules are
seen in Acacia
erioloba
8. Shrinkage
• Shrinkage occurs
when cells lose
turgidity.
•Animals may be
scared of fastmoving plants &
hence don’t eat
plants that shrink.
•Shrinkage is seen
in Mimosa pudica.
9. Milky Latex
• Milky Latex is an
aqueous secretion
that is poisonous.
• Milky Latex is
seen in Euphorbia
pulcherrima &
Opium poppy.
10. Trichomes
• Trichomes are hairlike projections from
the epidermis.
• There are glandular
hairs & nonglandular hairs.
• Non-Glandular
hairs are nonpoisonous but cause
irritation. E.g.
Capsicum pubescens
12. Volatile Organic
Compounds
(VOC’s)
• VOC’s are
chemical substances
produced by plants
that are used as a
defense mechanism.
• Geraniums produce
a chemical called
quisqualic acid that
paralyses insects
when they feed on
the plant.
13. Conclusion
• Hence, we have learnt that plants have a
variety of defense strategies, physical as well
as chemical defenses, that protect themselves
from enemies.
• Defense mechanisms are therefore needed by
plants to affect not just a single threat but
multiple threats.
14. Bibliography
Information acquired from:
• www.wikipedia.org, visited on 2nd August 2013
• www.geraniumsonline.com/trichomes, visited on
2nd August 2013
Images acquired from:
• www.wikipedia.org, visited on 2nd August 2013
• www.google.co.in, visited on 2nd August 2013
